Standard molding base



vwl VII I iw AprilV 23, 1946. 1. T. QUARNs'rRoM STANDARD MOLDING BASEFiled July 21. 1945 2 Sheets-Sheet 1 April 23, 1946.

|. T. QuARNsTRoM 2,398,893

STANDARD MOLDING BASE Filed July 21, 1943 2 Sheets-Sheet 2 I N V EN TOR.V141? TQq/YSTRM BY I AWO/PNE?? Patented Apr. 23, 1946 UNITED wvusn vul IIvar! STATES PATENT OFFICE 8 Claims.

This invention relates to a mold base employed for plastic injectionmolding, and more particularly to combination dowel and leader pinsemployed in conjunction with the mold base.

Heretofore in mold bases of this type numerous dowel pins and screws orstuds have been utilized for holding the various portions of the moldbase together and in proper alignment. It is the purpose of thisinvention to eliminate most of these pins and screws, substitutingmerely a plurality of combination dowel and leader pins foraccomplishing the same purpose.

It is the further purpose herein to utilize said dowel pins also asguide means for the reciprocable injector plate for providing smoothnonbinding movement thereof within the mold base.

This invention therefore relates to the various elements and theircombinations as more fully described in conjunction with theaccompanying drawings of which- Fig. 1 is an elevational view of themold base.

Fig. 2 is a partially sectioned plan view thereof, with front cavityretainer and anchor plates removed.

Fig. 3 is a fragmentary elevational section thereof.

Fig. 4 is a fragmentary elevational section of a slightly differentembodiment.

It will be understood that said drawings are merely illustrations ofpreferable embodiments of the invention, and that other embodiments arealso contemplated within the scope of the invention hereinafterdescribed and claimed.

Referring to the drawings Figs. 1, 3 and 4 show the standard mold basehaving a rectangular anchor plate II with two parallels I2 and I3disposed thereon and secured thereto in spaced relation. Said parallelsare placed inwardly of the sides of anchor plate II to provide extendingportions I4 and I5 to permit clamping thereof to a molding machine.

A back-up plate I6 rectangular in shape is D0- sitioned upon the topedges of parallels I2 and I3 providing means for supporting theremovable and interchangeable rear cavity retainer plate I1. Acorresponding front cavity retainer plate I8 is provided similar inshape to said rear cavity plate for compressive cooperative engagementwith respect thereto. Both the upper surface I9 of retainer plate I1 andthe lower surface 28 of retainer plate I8 are blank, but are adapted tohave impressed or cut therein, or inserted therein, corresponding andmating molds and cores within which is injected a plastic material to bemolded therein, in the manner hereafter set out.

Another anchor plate 23 corresponding to anchor plate II is suitablysecured to the front cavity plate I8 and similarly the edges 24 and 25of plate 23 extend beyond the edges of plate I8 to permit clampingthereof within a molding machine.

A rectangular ejector plate is indicated at 28 longitudinally disposedbetween the two parallels I2 and I3 and adapted for manually actuatedupward sliding movement therebetween. A secondary ejector plate 21secured upon ejector plate 26 is adapted to retain and secure in uprightposition at right angles thereto the push back pins 28 and 29.

Ejector pins 30 and 3I are shown in Fig. 1 as also secured by thesecondary ejector plate 21 to the ejector plate 2G, so as to upwardlyextend through openings in the back up plate IQ and also into openingswithin the core 32. 'I'he latter is provisioned by the mold maker withinthe rear cavity plate I1 in corresponding and cooperating alignedrelation to the mold 33 which is also provisioned within the frontcavity retainer plate I8.

It will be understood that the standard base shown in Fig. l does notinitially include the ejector pins 30 and 3I which are located asdesired by the mold maker to correspond with the positioning of themolds 32 and 33 within thefront and rear cavity retainer plates I1 andI8.

It is contemplated also that the stock base itself makes no provisionfor the molds 32 and 33 or their positioning within the blanked frontand rear cavity retainer plates, inasmuch as their shape and positioningwill differ, being dependent upon the particular molding jobcontemplated by the mold maker.

Referring to Figs. 1, 3 and 4 it is Seen that upon outward movement ofthe ejector plate 26 that in addition to upward movement of ejector pins30 and 3|, a corresponding upward movement is given to the push backpins 28 and 23 previously described. Their downward position isindicated in Fig. 1. When the two cavity retainer plates are againbrought together within a suitable molding machine the outer ends ofpush back pins 28 and 29 engage the surface 20 of the front cavityretainer plate I8, whereby the ejector plate 26 is forced back intoneutral position.

In operation in carrying out injection molding thetwo cavity retainerplates I1 and I8 are tightly brought together and a plastic moldingmaterial is supplied through the hollow locator 31 and into the nozzle38 as shown in Fig. 1, for injection into the molds 32 and 33.

The standard base shown in Fig. 1 is also provided with a sprue puller39 which extends upwardly and at right angles to the ejector plate 26and the secondary plate 21 which secures the same to said ejector plateas shown.

Said sprue puller is merely a cylindrical pin having at its outer end anirregular undercut edge 40 within which a portion of the plasticmaterial is fed when the molding material is injected into the moldsprovisioned Within the two cavity retainer plates I1 and I8,

When the plastic material has hardened a sprue is formed interconnectingeach of the molded pieces within the corresponding molds, extending alsopartially up into the opening within the nozzle 38 and also extendingdown into the portion 40 of the sprue puller 39.

The purpose of the sprue puller is to retain the sprue within the rearcavity retainer plate I1 as the same is withdrawn from the stationaryretainer plate I8 and thus prevent sticking of the sprue within thenozzle opening, which might tend to damage the sprue and the moldedparts connected thereto.

Fig. l illustrates the construction of the ejector plate 26 which ismaintained initially in spaced relation to the adjacent anchor plate I Iby means of the studs 4I.

For the purpose of simplicity only one mold is shown in Fig. 1 at 32 and33 within the corresponding cavity retainer plates I1 and I8, however itis contemplated that any number of molds may be provisioned thereindepending upon the molding job contemplated.

Figs. l and 3 show the four combination dowel and leader pins or shafts42 transversely disposed through corresponding openings in anchor plateI I, back-up plate I6 and the rear cavity retainer plate I1.

Socket headed cap screws 43 are provisioned through the bottom of anchorplate II, and are adapted for threaded securing engagement with thebottom ends of dowel shafts 42 at 44, whereby said shaft may beremovably, but firmly held within the mold base and particularly membersII, I6 and I1.

The upper annular collar portion 4-5 of shaft 42 nesting within acorresponding annular recess 46 in the rear cavity plate I1, terminatesin the upwardly extending front cavity engaging member 41. Portion 41then slidingly extends through the bushing 48 within front cavityretainer plate I8 and also into a corresponding opening in the anchorplate 23.

Fig. 2 is a plan View of the mold base with the front cavity plate I8and corresponding anchor plate 23 withdrawn, as is the case when the tworetainer plates I1 and I8 are supported within a molding machine.

The upper extending portions 41 of the four dowel shafts 42 shown inFig. 2, are thus adapted to be slidingly received by fourcorrespondingly arranged bushings 48 disposed within suitable openingsin the front cavity retainer plate I8, as the latter and its anchorplate are correspondingly brought towards the rear cavity plate I1within a suitable molding machine.

Thus the proper alignment is obtained between the two cavity retainerplates I1 and I8 as they are brought together prior to the injectionmolding operation. This consequently guarantees that the core 32disposed within cavity plate I1 will vthe four spaced bushings 49disposed therethrough with their openings coinciding in alignment withthe combination dowel and leader pins 42 shown in Fig. 2 for slidingengagement therewith.

It is noted also that the ejector plate 26 is provided with fouroutwardly extending arcuate flanged portions 50 within which saidbushings 49 are disposed. Correspondingly arcuately notched recesses 5Iare also formed within the back-up plate supporting members I2 and I3within which the ejector plate flanged portions 50 are disposed asindicated in Fig. 2.

A plurality of guiding means are thus provided for the ejector plate 26whereby the same slidingly engages the combination leader and dowel pins42.

A slightly different type of dowel pin arrangement is shown in Fig. 4wherein the four leader pins 52 are employed in place of the leader pins42 shown in Fig. 3. Said leader pins or shafts 52 are transverselydisposed through corresponding openings in anchor plate II, back-upplate I6, and the rear cavity retainer plate I1.

Socket headed cap screws 53 are provisioned through the bottom of anchorplate II adapted for threaded engagement with the bottom ends of shafts52 at points 54, whereby said shafts 52 are secured removably within theportion of the mold base including members II, I6 and I1.

The upper annular collar portions 5-5 of shafts 52 nesting withincorresponding annular recess 56 in rear cavity plate I1 has providedthrough its top portion downwardly projecting recesses 51 terminating inthe air conduits 58 as shown in Fig. 4.

The four corresponding dowel pins 59 project downwardly from the frontcavity retainer plate I8, and anchor plate 23, and are adapted to beslidingly and cooperatively received within the four correspondingrecesses 51 aligned therewith within leader pins 52.

Air passages 58 provide for the escape of air,

which in their absence would result in air cornpression within recesses51, possibly preventing the front cavity retainer plate from properlyengaging the rear cavity plate I1. Here again sultable bushing" 49 areemployed exactly as described in connection with Figs. 2 and 3, beingdisposed through the ejector plate 26, Within their openings inalignment with the four leader pins 52, with which they are adapted forcooperative sliding engagement.

The arrangement of the flanged arcuate portions 50 and correspondingrecesses 60 in the ejector plate 26 and the spacer support I3respectively, are the same as that shown in Fig. 2.

It is seen that the leader pins 52 in combination with the mating dowelpins 59 and bushings 49 provide not only means for maintaining the moldbase securely, but also provide suitable guide means for the ejectorplate 26.

The essential purpose of the present invention is to provide a means forretaining the molding base and its constituent elements in immovablerelation for the injection molding operation. And this is accomplishedas shown in Fig. 3 by the combination leader and dowel pins 42,retaining studs 43, and bushings 48 disposed within the front cavityretainer plate I8.

It is noted in Fig. 4 that a similar result is obtained by thecombination leader pins 52 cooperatingly engaged by the dowel pins 59Dowel pins 59 disposed within the front cavity retainer plate I8 alsoextend partially into anchor plate 23 providing an immovablerelationship therebetween. Furthermore suitable socket headed retainingstuds 6| are disposed downwardly through anchor plate 23 for threadedengagement at 62 with the top portions of the dowel pins 59.

Thus it is seen that the embodiment of the combination dowel and leaderpin arrangement shown in Fig. 4 is effective not only in maintaining therespective elements of the mold base in proper alignment, but alsoprovides means for positively securing said elements in the relationshipshown in Fig. 4.

Having described my invention, reference should now be had to the claimswhich follow for determining the scope thereof.

I claim:

l. In a stock base for injection plastic molding, an anchor plateadaptable for attachment to the movable member of a molding machine,upright parallel members in spaced relation carried by said plate, aback-up plate carried by said parallel members, a rear cavity retainerplate secured upon said back-up plate; an anchor plate adapted forattachment to the stationary member of a molding machine, a front cavityretainer plate carried by said stationary anchor plate, a reciprocableejector plate interposed between said y parallel members, a plurality ofleader pins with central longitudinal recesses in one of the endsthereof, disposed and secured through said movable anchor plate, ejectorplate, back-up plate and rear cavity plate, a plurality of dowel pinsextending from said front cavity plate adapted for cooperative slidingengagement with the corresponding openings in said leader pins, andbushings disposed through said ejector plate, in alignment with saidleader pins providing for cooperative sliding engagement therewith.

2. In a mold for injection plastic molding, a movable anchor plate, arear cavity retainer plate carried thereby, a stationary anchor plate, afront cavity retainer plate carried thereby, a plurality of leader pinsretainingly engaging said rear retainer plate at one of their ends andextending therethrough and with their other ends extending into saidmovable anchor plate, means securing said other ends to said movableanchor plate, said pins having longitudinal recesses in said one oftheir ends, and a plurality of dowel pins extending from said frontretainer plate in coaxial relation with said leader pins adapted forcooperative sliding engagement within the corresponding recesses in saidleader pins.

3. In a stock base for injection plastic molding, an anchor plateadaptable for attachment to the movable member of a molding machine,upright parallel members in spaced relation carried by said plate, aback-up plate carried by said parallel members, a rear cavity retainerplate secured upon said back-up plate; an anchor plate adaptable forattachment to the stationary member of a molding machine, a front cavityretainer plate carried by said stationary anchor plate, awnozzledisposed within said stationary anchor and retainer plates through whichplastic material may be forced into the cavities between said cavityretainer plates to form the article, a plurality of leader pinsretainingly engaging said rear retainer plate at one of their ends andextending therethrough and through said back-up plate, with their otherends extending into said movable anchor plate, means securing said otherends to said anchor plate, said pins having longitudinal recesses insaid one of their ends, and a plurality of dowel pins extending fromsaid front cavity retainer plate in coaxial relation with said leaderpins adapted for cooperative sliding engagement within the correspondingrecesses in said leader pins.

4. In a stock base for injection plastic molding, an anchor plateadaptable for attachment to the movable member of a molding machine,upright parallel members in spaced relation carried by said plate, aback-up plate carried by said parallel members, a rear cavity retainerplate secured upon said back-up plate; an anchor plate adapted forattachment to the stationary member of a molding machine, a front cavityretainer plate carried by said stationary anchor plate, a plurality ofleader pins retainingly engaging said rear retainer plate at one oftheir ends and extending therethrough and through said back-up platewith their other ends extending into said movable anchor plate, meanssecuring said other ends to said anchor plate, said pins havinglongitudinal recesses in said one of their ends, and a plurality ofdowel pins extending from said front retainer plate in coaxial relationwith said leader pins adapted for cooperative sliding engagement withinthe corresponding recesses in said leader pins.

5. In a stock base for injection plastic molding, an anchor plateadapted for attachment to the movable member of a molding machine,upright parallel members in spaced relation carried by said plate, aback-up plate carried by said parallel members, a rear cavity retainerplate secured upon said back-up plate; an anchor plate adapted forattachment to the stationary member of a molding machine, a front cavityretainer plate carried by said stationary anchor plate, a, plurality ofleader pins retainingly engaging said rear retainer plate at one oftheir ends and extending therethrough and through said back-up platewith their other ends extending into said movable anchor plate, meanssecuring said other ends to said anchor plate, said pins havinglongitudinal recesses in said one of their ends, a plurality of dowelpins extending from said front retainer plate in coaxial relation withsaid leader pins adapted for cooperative sliding engagement within thecorresponding recesses in said leader pins, and means disposed throughsaid stationary anchor plate engaging said dowel pins for securing thesame thereto.

6. In a stock base for injection plastic molding, an anchor plateadaptable for attachment to the movable member of a molding machine,upright parallel members in spaced relation carried `by said plate, aback-up plate carried by said parallel members, a rear cavity retainerplate secured upon said back-up plate; an anchor plate adapted forattachment to the stationary member o! a molding machine, a front cavityretainer plate carried by said stationary anchor plate, a reciprocableejector plate interposed between said parallel members, a plurality ofleader pins secured to said movable anchor plate at one of their endsand disposed through said ejector plate and backup plate and retaininglyengaging said rear cavity plate at their other ends, said pins havinglongitudinal recesses in said other ends, and a plurality of dowel pinsextending from said front cavity plate in coaxial relation with saidleader pins adapted for cooperative sliding engagement within thecorresponding recesses in said leader pins, said ejector plate having aplurality of spaced openings through which said leader pins extend forsliding engagement therewith.

7. In a stock base for injection plastic molding, an anchor plateadaptable for attachment to the movable member of a molding machine,upright parallel members in spaced relation carried by said plate, arear cavity retainer plate secured upon said parallel members; an anchorplate adapted for attachment to the stationary member of a moldingmachine, a front cavity retainer plate carried by said stationary anchorplate, a plurality of leader pins retainingly engaging said rearretainer plate at one of their ends and extending therethrough withtheir other ends extending into said movable anchor plate, meanssecuring said other ends to said anchor plate, said pins havinglongitudinal recesses in said one of their ends, and a plurality ofdowel pins extending from said front retainer plate in coaxial relationwith said leader pins adapted for cooperative sliding engagement withinthe correspondlng recesses in said leader pins.

8. In a stock base for injection plastic moldmg, an anchor plateadaptable for attachment to the movable member of a molding machine,upright parallel members in spaced relation carried by said plate, arear cavity retainer plate secured upon said parallel members; an anchorplate adapted for attachment to the stationary member of a moldingmachine, a front cavity retainer plate carried by said stationary anchorplate, a reciprocable ejector plate interposed between said parallelmembers, a plurality of leader pins secured to said movable anchor plateat one oi' their ends and disposed through said ejector plate andretainingly engaging said rear cavity plate at their other ends, saidpins having longitudinal recesses in said other ends, and a plurality ofdowel pins extending from said front cavity plate in coaxial relationwith said leader pins adapted for cooperative sliding engagement withinthe corresponding recesses in said leader pins, said ejector platehaving a plurality of spaced openings through which said leader pinsextend for sliding engagement therewith.

IVAR T. QUARNSTROM.

